Function-Material EPR Pole Pieces for Eddy Current Suppression
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Solution Overview
Problem
EPR spectrometers face issues with eddy currents induced in pole pieces by modulation coils, leading to increased power consumption, noise, and thermal instability, which can be mitigated by using conventional iron pole pieces but at the cost of larger, more expensive magnet systems.
Innovation Solution
Using pole pieces made from function materials with low electric conductivity and high saturation magnetic flux density, allowing modulation coils or rapid scan coils to be placed closer without inducing significant eddy currents, thereby reducing noise and power consumption while maintaining magnetic field homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional iron pole pieces are used, then magnetic field strength and homogeneity are improved, but eddy currents are induced by modulation coils leading to increased power consumption and noise
Solution Approach 1:
The invention changes the material parameter of the pole piece from conventional iron (high electrical conductivity) to a function material with low electrical conductivity (σf ≤ 10^4 S/m) and high saturation magnetic flux density (BSf ≥ 0.2 T). This parameter change reduces eddy current induction while maintaining magnetic field generation capability, thereby reducing power consumption and thermal instability.
Solution Approach 2:
The invention employs a function material that combines magnetic properties (for field generation) with low electrical conductivity (for eddy current suppression). This composite material approach allows the pole piece to simultaneously achieve good magnetic field homogeneity and reduced eddy current losses, resolving the contradiction between magnetic performance and energy efficiency.
2Volume of moving object
If modulation coils are placed close to iron pole pieces, then device compactness is improved, but eddy currents increase causing noise and reduced coil efficiency
Solution Approach 1:
By changing the electrical conductivity parameter of the pole piece material to a low value (σf ≤ 10^4 S/m), the invention enables the modulation coil to be placed close to the pole piece without inducing significant eddy currents. This maintains device compactness while suppressing noise generation from eddy currents and preserving coil efficiency.
3Stability of the object's composition
If larger magnet systems are used, then magnetic field homogeneity is improved, but device size and cost increase
Solution Approach 1:
The invention changes the material composition of the pole piece to a function material with optimized magnetic properties (high saturation flux density) and low electrical conductivity. This allows achieving good magnetic field homogeneity in a compact magnet system size, as the function material efficiently generates and maintains the required magnetic field without requiring an oversized magnet system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves a noise reduction of 3 to 10 times and allows for a compact, cost-effective EPR spectrometer with reduced thermal instability and acoustic vibrations, enabling efficient EPR measurements.
Implementation Method 1
arranging a modulation coil or rapid scan coil adjacent to such a pole piece, when operating the modulation or rapid scan coil, can induce circular electric currents in the electrically conducting pole piece. These so-called eddy currents generate a magnetic field opposed to the variation of magnetic field generated by the modulation coils
Implementation Method 2
a magnet system, comprising at least one magnet and at least one pole piece, preferably a pair of mutually opposing pole pieces, for producing a magnetic field in a field of view in front of the pole piece or between the pair of pole pieces, wherein said magnetic field is generated along a pole axis
Implementation Method 3
a probe head, comprising a microwave resonator and at least one modulation coil or rapid scan coil for producing an additional, time-varying magnetic field aligned along the pole axis
Data Source
AI summary
An electron paramagnetic resonance (EPR) spectrometer includes a magnet system comprising at least one magnet and at least one pole piece for producing a magnetic field along a pole axis in a field of view in front of the at least one pole piece. A probe head comprising a microwave resonator and at least one modulation coil or rapid scan coil produces an additional, time-varying magnetic field aligned along the pole axis. The probe head is arranged in the field of view, and a respective modulation coil or rapid scan coil is arranged between the microwave resonator and a respective pole piece. For each pole piece, at least a part of said pole piece is made of a function material having an electric conductivity σf of 104 S/m or less, and having a saturation magnetic flux density BSf of 0.2 T or more.